scholarly journals Ultrastructure and energy-dispersive x-ray microanalysis of cartilage after rapid freezing, low temperature freeze drying, and embedding in Spurr's resin.

1985 ◽  
Vol 33 (10) ◽  
pp. 1073-1079 ◽  
Author(s):  
J Appleton ◽  
R Lyon ◽  
K J Swindin ◽  
J Chesters
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Energy Dispersive ◽  
Freezing Process ◽  
Rapid Freezing ◽  
Thin Sections ◽  
X Ray ◽  
Freeze Dried ◽  
Rapid Production ◽  
Ideal Method

In order to undertake meaningful high-resolution x-ray microanalysis of tissues, methods should be used that minimize the introduction of artefacts produced by loss or translocation of ions. The most ideal method is rapid freezing but the subsequent sectioning of frozen tissues is technically difficult. An alternative method is to freeze dry the tissues at a low temperature, and then embed them in resin. This facilitates the rapid production of reproducible thin sections. With freeze-dried, embedded hypertrophic cartilage, the morphology was similar to that seen using aqueous fixatives even when no additional electron density is introduced by the use of osmium vapor. Energy-dispersive analysis of specific areas show that little or no loss or migration of ions occurs from structures such as mitochondria. Mitochondrial granules consisting of calcium and phosphorus precipitates were not observed except where the cells were damaged as a result of the freezing process. This may suggest that these granules only appear when tissue is damaged because of inadequate preservation.

Thin sectioning, freeze fracturing, energy dispersive x-ray analysis, and chemical analysis in the study of inclusions in seed protein bodies: almond, Brazil nut, and quandong

1978 ◽  
Vol 56 (17) ◽  
pp. 2050-2061 ◽  
Author(s):  
John N. A. Lott ◽  
Mark S. Buttrose
Keyword(s):  
Chemical Analysis ◽  
Freeze Fracture ◽  
Prunus Dulcis ◽  
Energy Dispersive ◽  
Protein Bodies ◽  
Brazil Nut ◽  
Fixed Tissue ◽  
Thin Sections ◽  
X Ray ◽  
Freeze Dried

Protein bodies from almond (Prunus dulcis), Brazil nut (Bertholletia excelsa), and quandong (Santalum acuminatum) have been studied in thin sections of fixed and embedded tissue, in freeze-fracture replicas of unfixed tissue, by chemical analysis of tissue for P, K, Mg, and Ca, and by energy dispersive x-ray (EDX) analysis of both sections of glutaraldehyde-fixed tissue and freeze-dried tissue powders. The protein bodies in all three species contained globoid crystals, protein crystalloids, and proteinaceous matrix regions. Results of EDX analyses were consistent with globoid crystals being rich in phytin. Variation in both the structure and the elemental composition of globoids was common. In almond some globoids were lobed rather than spherical, and large globoid crystals often contained considerable calcium whereas small globoid crystals contained little if any calcium. The globoid crystals of Brazil nut often contained barium in addition to P, K, Ca, and Mg. Protein crystalloids of Brazil nut were compound crystals. Protein bodies of quandong seed, which is largely endosperm rather than embryo, were unexceptional.

Freezing and freeze-drying

1975 ◽  
Vol 191 (1102) ◽  
pp. 9-19 ◽  
Keyword(s):  
Low Temperature ◽  
Freeze Drying ◽  
Storage Temperature ◽  
Research Work ◽  
High Water Content ◽  
Freezing Process ◽  
Neutral Atmosphere ◽  
Reduced Pressure ◽  
Freeze Dried ◽  
Frozen State

Most biological substances are unstable during storage owing to their high water content. This is why numerous attempts have been made over the last 100 years to prevent, by low temperature freezing, metabolic and biochemical degradations. The transformation of water into ice brings to an end all chemical reactions; however, it might also induce deleterious alterations into the delicate structure of many products. A brief review of the basic phenomena involved in the freezing process of biological substances helps to understand how the cooling cycles, storage temperature and subsequent rewarming have to be monitored in each individual case. Despite the fact that preservation in the frozen state offers wide possibilities, it is still difficult to apply in some instances, since it implies a continuous low temperature storage and transportation. This is why freeze-drying, or lyophilization, has been introduced. It is a two-step process in which the products to be preserved are deep frozen first, then dried by direct sublimation of the ice under reduced pressure. When completely dehydrated the substances can be stored almost indefinitely if kept in a dry, neutral atmosphere and in the dark. Fundamental aspects of the freeze-drying process will be discussed. Recent research work has shown that drying by sublimation from the frozen state can be performed with other systems than aqueous media. Solutions of lipophilic compounds, fats, phospholipids, steroids, in organic solvents can be ‘freeze-dried’ at low temperatures and high velocities. This particular technology opens new fields for the preservation of delicate materials of living origins.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

ENERGY DISPERSIVE X-RAY ANALYSIS OF FIELD PEAS WITH DIFFERENT COOKING QUALITY

1983 ◽  
Vol 63 (4) ◽  
pp. 1071-1074 ◽  
Author(s):  
J. CHONG ◽  
S. T. ALI-KHAN ◽  
B. B. CHUBEY ◽  
G. H. GUBBELS
Keyword(s):  
Statistical Analysis ◽  
Pisum Sativum ◽  
Cooking Quality ◽  
Energy Dispersive ◽  
Protein Bodies ◽  
X Ray ◽  
Pisum Sativum L ◽  
Field Peas ◽  
Freeze Dried ◽  
High Concentrations

An energy dispersive X-ray (EDX) analytical method was used to study the freeze-dried powder of seeds of field peas (Pisum sativum L.) with good and poor cooking quality. EDX analysis of the electron-dense particles in the freeze-dried powder revealed the presence of high concentrations of Mg, P, and K, suggesting that the particles were protein bodies. Seeds with different cooking quality were compared with respect to the ratios of these elements in the dense particles. Statistical analysis indicated a significant correlation between these ratios and cooking quality.Key words: Pisum sativum, protein bodies, elemental analysis

Composition and Microstructure of a Furnace Ash Deposit from a Coal-Fired Utility Boiler

1980 ◽  
Vol 102 (3) ◽  
pp. 692-697
Author(s):  
R. R. Fessler ◽  
A. J. Skidmore ◽  
H. R. Hazard ◽  
J. P. Dimmer
Keyword(s):  
Iron Oxide ◽  
Low Temperature ◽  
Energy Dispersive ◽  
Spherical Particles ◽  
Tube Surface ◽  
X Ray ◽  
Melting Temperatures ◽  
Coal Particles ◽  
Wide Range ◽  
Ash Deposit

An exploratory study of the structure and composition of furnace-ash deposits was carried out using optical metallography, electron microprobe analysis, scanning electron microscopy, and energy-dispersive X-ray analysis. The results of these analyses were supplemented by studies of particulate melting temperatures using hot-stage microscopy to measure melting temperatures, and energy-dispersive X-ray analyses to measure composition of melted particles. It was found that the general structure of the ash deposit was a matrix of glassy, spherical particles having a wide range of compositions in which unfused particles containing iron oxide and calcium oxide were dispersed. At the imprint of the tube surface a considerable concentration of calcium, sulfur, and iron was found. Near the fused outer surface of the deposit, the glassy materials had melted into a porous, glassy slag containing spherical globules of iron oxide combined with other materials. There were no systematic compositional gradients from the tube surface to the fused outer layer except for the sulfur layer found only at the tube surface. However, there were significant differences in composition from particle to particle, and these differences were similar to those found in the coal mineral matter as isolated by low-temperature ashing. Single particles of low-temperature ash were found having low fusion temperatures, in the range of fusion temperatures for particles in furnace ash. Thus, the glassy spheres found in furnace deposits could originate from single coal particles, without the need for interactions among coal particles or ash particles.

An energy dispersive x-ray analysis study of elemental loss from globoid crystals in protein bodies as a result of osmium tetroxide fixation

1978 ◽  
Vol 56 (19) ◽  
pp. 2408-2414 ◽  
Author(s):  
J. N. A. Lott ◽  
J. S. Greenwood ◽  
C. M. Vollmer
Keyword(s):  
Osmium Tetroxide ◽  
Juglans Regia ◽  
Energy Dispersive ◽  
Protein Bodies ◽  
X Ray ◽  
Edx Analysis ◽  
Freeze Dried ◽  
Major Loss ◽  
Degree Of Extraction ◽  
Helichrysum Bracteatum

This study was undertaken to discover what elemental losses, if any, were occurring from globoid crystals in seed protein bodies during glutaraldehyde – osmium tetroxide fixation. Unfixed cotyledon and radicle tissue of Cucurbita maxima seed, or tissue after glutaral–dehyde–OsO4 treatment, was quick frozen in liquid N2, ground with a cold mortar and pestle, and low-temperature freeze-dried. Globoid crystals in the freeze-dried powder were subjected to energy dispersive x-ray (EDX) analysis. OsO4 fixation resulted in a major loss of P, Mg, and K from cotyledon globoid crystals and a major loss of P, Mg, K, and Ca from radicle globoid crystals. Despite the loss of elements, the OsO4-fixed globoid crystals were still electron dense. When globoid crystals from glutaraldehyde-fixed, dehydrated, and embedded cotyledon tissue were compared with globoid crystals from glutaraldehyde–OsO4-fixed, dehydrated, and embedded tissue, some extraction was found. The degree of extraction varied from complete loss of P, K, and Mg to loss of K only.Effects of glutaraldehyde–OsO4 fixation upon elemental composition of globoid crystals in several other species was also determined. Brazil nut (Bertholletia excelsa) radicle tissue or cotyledon tissue from walnut (Juglans regia), hazelnut (Corylus avellana), sunflower (Helianthus annuus), golden everlasting daisy (Helichrysum bracteatum), cashew (Anacardium occidentale), pistachio (Pistacia vera), and the Western Australian red-capped gum (Eucalyptus erythrocorys) were fixed either in glutaraldehyde or in glutaraldehyde–OsO4. In these species, EDX analysis of globoid crystal sections showed that OsO4 fixation results in major loss of Mg, K, and Ca. Generally, phosphorus levels were reduced from control values as well. When carrying out EDX analysis studies of globoid crystals, we recommend (1) avoiding any use of OsO4, (2) keeping all fixation, washing, and dehydration times as short as possible, and (3) checking all observations with freeze-dried powders.

Synthesis of Porous Ceramics Through Directional Solidification and Freeze-Drying

2003 ◽  
Vol 788 ◽  
Author(s):  
Predrag Kisa ◽  
Patrick Fisher ◽  
Al Olszewski ◽  
Ian Nettleship ◽  
Nicholas G. Eror
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Porous Ceramics ◽  
Porous Structures ◽  
Directionally Solidified ◽  
X Ray Diffraction ◽  
Microstructural Characteristics ◽  
X Ray ◽  
Freeze Dried ◽  
Silica Sols

ABSTRACTThis study investigated the microstructural characteristics of directionally solidified freeze-dried silica sols. Porous structures were formed by depositing silica sol on silicon (100) single crystals. The deposited sols were unidirectionaly solidified by placing the silicon substrate on a copper block immersed in liquid nitrogen and then subsequently freeze-dried. Freeze drying removal of ice crystals created three-dimensional pore channels ranging from 3 to10 micrometers in diameter aggregated in grain like colonies 50–100 micrometers in diameter. Pore size, spacing, colony size and microstructure were determined using optical microscopy (OM) and scanning electron microscopy (SEM) while the structure of the amorphous SiO2 was characterized by X-ray diffraction (XRD). The microstructure results are compared and contrasted with silica aerogel obtained through conventional processing using supercritical CO2.

Aluminium Distribution in Freeze-Dried Roots of Cabbage, Lettuce and Kikuyu Grass by Energy-Dispersive X-Ray Analysis

1980 ◽  
Vol 7 (1) ◽  
pp. 101 ◽  
Author(s):  
DO Huett ◽  
RC Menary
Keyword(s):  
Emission Spectra ◽  
Energy Dispersive ◽  
Poor Correlation ◽  
Cortical Cells ◽  
X Ray ◽  
Freeze Dried ◽  
Back Ground ◽  
The Mean ◽  
Kikuyu Grass ◽  
And Control

The aluminium distribution in transverse sections of fractured and freeze-dried roots of cabbage, lettuce and kikuyu grass was studied by energy-dispersive X-ray analysis. The mean ratios of the integrated counts corresponding to Kα emission spectra for aluminium, phosphorus and silicon were recorded between aluminium and control treatments over three experiments. Peak-to-back- ground ratios (PA/B) were calculated and the aluminium ratios corrected for variations in the corresponding total silicon ratios. Aluminium was found to be uniformly distributed along roots of the three species. The highest peaks (PA) and peak-to-background ratios, suggesting higher concentrations, were recorded in the epidermis followed by the cortex. Aluminium was recorded in the stele of all species and in the protoplasm of cortical cells, with smaller amounts in the protoplasm of xylem parenchyma cells for lettuce and kikuyu grass. The distribution of aluminium supports the hypothesis that its entry to the stele can be achieved by transport both into meristematic cells and the symplasm via the cortex and hence bypassing the barrier at the endodermis. The latter evidence was supported by the presence of aluminium in the radial wall (and cytoplasm) of the endodermis for each species. There was a poor correlation between the distribution of aluminium and phosphorus.

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